Waveguide junction circulator having impedance matching wedge at the junction



Feb. 3, 1970 3,493,896 WAVEGUIDE JUNCTION CIRCULATOR HAVING IMPEDANCE MATCHING WEDGE AT THE JUNCTION 7 Filed Nov 29, 1967 7 ,1. 11 IMPEDANCE MATCHING WEDGE INVENTOR. GERHARO HJCHTA AGENT FIG. 2

FERRITE "United States Patent 3,493,896 WAVEGUIDE JUNCTION CIRCULATOR HAVING IMPEDANCE MATCHING WEDGE AT THE JUNCTION Gerhard Buchta, Hamburg, Germany, assignor to US.

Philips Corporation, New York, N.Y.

Filed Nov. 29, 1967, Ser. No. 686,582

Int. Cl. H01 H32 US. Cl. 3331.1 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a microwave circulator having a wave-guide series branching, in which one branch is at right angles to the larger side of the continuous waveguide, a symmetrical wedge-shaped metallic obstacle being arranged in the continuous waveguide opposite to the junction and, in parallel therewith, a ferrite body which is premagnetised in the same direction and which does not extend through the full width of the waveguide.

From Proc. IRE, November 1959, page 2018, a microwave circular having a ferrite body and a wave-guide series branching is known in which one branch is at right angles to the larger side of a continuous waveguide and in which a ferrite body premagnetized in the axial direction is arranged in the waveguide in the region of the junction.

From British patent specification No. 665,434 it is known, in order to improve the impedance match in a wave-guide series branching in which one branch is at right angles to the larger side of the continuous waveguide, to arrange a symmetrical wedge-shaped metallic obstacle in the continuous waveguide opposite to the junction.

From the German utility sample No. 1,923,472 a broadband adjustable circular is known which comprises at least three co-planar waveguide sections and which includes, at the central junction transverse to the said plane, a premagnetised ferrite body and also elements for adjusting the blocking damping or impedance match. In this arrangement the ferrite body is attached to one broad side of the continuous waveguide which is adjacentto the junction.

The present invention is based on this state of the art and provides an arrangement for obtaining satisfactory decoupling, for example greater than 20 db, between the various waveguide sections of more particularly very short structural length, while also increasing the bandwidth, for example in the radar band, relative to conventional arrangements.

To solve this problem for a microwave circular of the kind mentioned in the preamble, the invention suggests to arrange further electrically conductive bodies in approximately axial direction with the ferrite body.

According to the invention the waveguide may include, in the axial direction with the ferrite body, two electrically conductive bodies one of which lies between the ferrite body and the wall of the waveguide and the other of which lies on the opposing wall of the waveguide. The electrically conductive bodies may be secured to the walls of the waveguide in such manner that their depth of penetration in the waveguide is variable. Furthermore 3,493,896 Patented Feb. 3, 1970 the ferrite body and/or the electrically conductive bodies may be additionally covered with a dielectric body.

A microwave circular according to the invention has, for example in the radar band, a bandwidth greater than 1 gc./s. It may govern, for example, the whole of the radar band (8.5 to 9.6 gc./s.) and has a minimum decoupling of 20 db at the band limits and a comparably low insection loss which is less than 0.5 db.

In order that the invention may be readily carried into effect one embodiment thereof will now be described in detail, by way of example, with reference to the accompanying diagrammatic drawing, in which:

FIGURE 1 is a prespective view of a microwave circuliator which is shown partly cut away at the junction, an

FIGURE 2 is a cross-section through the centre of the junction with the branch.

FIGURES 1 and 2 show a continuous waveguide 1 having a length of, for example, approximately 12.5 mm. and a branch at 2. At the junction a metal obstacle 4 lies on one broad wall 3 of the waveguide. Electrically conductive bodies 7 and 8 are secured with depths 9 and 10 to the narrow walls 5 and 6 of the waveguide, the heights 9 and 10 being equal to the depth of penetration of the electrically conductive bodies 7 and 8. The electrically conductive body 7 carries a ferrite body 11.

The electrically conductive bodies 7 and 8 and the ferrite body 11 relatively extend in the axial direction. They may be arranged to be adjustable in the axial direction by corresponding means which pass through the walls 5 and 6 of the waveguide.

The electrically conductive bodies 7 and 8 constitute an inductive load. According to the invention the ferrite body 11 may have direct contact with the conductive body 7. The greater the depth of penetration of the bodies 7 and 8 into the waveguide, the higher will be the inductive load. The depths of penetration and the diameters of the parts 7, 8 and 11 are determined by the strength of the external magnetic field H, the desired range of frequencies and the materials or ferrite materials used. In order to reduce the losses, the electrically conducitve bodies 7 and 8 must be connected to the walls 5 and 6 in a conducitve manner. According to the invention, in order to improve the broadband properties, the ferrite body 11 may be covered with a dielectric body.

What is claimed is:

1. A microwave circulator comprising a first rectangular waveguide section, a second rectangular waveguide section connected to one wide wall of said first section, and elongated symmetrical wedge-shaped metallic body in said first waveguide section on the other wide wall thereof opposite the junction with said second waveguide section, said wedge-shaped body extending normal to the axis of said first waveguide section, a ferrite body in said first waveguide section aligned with said junction, first and second conductive bodies connected to opposite narrow walls of said first section on opposite sides of said ferrite body, and means producing a magnetic field in said ferrite body parallel to said wedge-shaped body.

2. A microwave circulator as claimed in claim 1 wherein one of said conductive bodies lies between the ferrite body and one wall of the first waveguide and the other of said conductive bodies lies on the opposing wall of the first waveguide.

3. A microwave circulator as claimed in claim 1 wherein the electrically conductive bodies are secured to the walls of the waveguide in such manner that their depths of penetration in the Waveguide are variable.

4. A microwave circulator as claimed in claim 1 wherein the ferrite body is additionally covered with a dielectric body.

5. A microwave circulator as claimed in claim 1 where- 3,072,870 1/1963 Walier 33.3-33 X glattgirealconductive bodies are coated with a dielectric HERMAN KARL SAALBACH Primary Examiner References Cited P. L. GENSLER, Assistant Examiner UNITED STATES PATENTS 5 CL 3,070,760 12/1962 Wheeler 33324.2 X 33333 

